\documentclass[multi=tikzpicture]{standalone}

\usepackage[T1]{fontenc}
\usepackage{pslatex}
\renewcommand*\ttdefault{txtt}
\usepackage{tikz-timing}
\usetikztiminglibrary[rising arrows]{clockarrows}
\usetikztiminglibrary{either}

\begin{document}

\begin{tikztimingtable}[
font=\tt,
timing/yunit=2.5ex,
timing/xunit=3ex,
timing/text format=\raisebox{.4ex}\strut\tt\Large,
timing/u/background/.style={fill=lightgray},
timing/e/background/.style={fill=lightgray}
]
{clock}     & [L] 20{C} \\
{reset} & 2.1E  2H    14L        1.9L \\
{tick}   & .1U 4U 4L  2H 4L 2H  2L 1.9L \\
{counter}   & .1U 4U  2D{0}  2D{1}   2D{2} 2D{0} 2D{1} 2D{2}  2D{0} 1.9D{1}  \\
\extracode
\vertlines[semitransparent, dashed]{2,4,6,8,10,12, 14, 16, 18}
\endextracode
\end{tikztimingtable}

\end{document}
